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PRODUCT DATASHEET
AAT3687
BatteryManagerTM
General Description
The AAT3687 BatteryManager is a highly integrated single-cell lithium-ion/polymer battery charger IC designed to operate with AC adapter inputs. It requires a minimum number of external components. The AAT3687 precisely regulates battery charge voltage and current for 4.2V lithium-ion/polymer battery cells. Adapter charge current rates can be programmed up to 1.5A. An active thermal management system regulates the fast charge constant current for all ambient temperature and input vs. output voltage conditions. Battery temperature and charge state are fully monitored for fault conditions. In the event of an over-voltage or over-temperature failure, the device will automatically shut down, thus protecting the charging device, control system, and the battery under charge. Status monitor output pins are provided to indicate the battery charge status by directly driving two external LEDs. A serial interface output is available to report 12 various charging status states to a microcontroller. The AAT3687 is available in a Pb-free, thermally-enhanced, space-saving 12-pin TDFN 3x3mm package and is rated over the -40C to +85C temperature range.
Lithium-Ion/Polymer Battery Charger
Features
* * * * Input Voltage Range: 4.0V to 5.5V Up to 1.5A Charging Current Adapter Present Indicator (ADPP#) High Level of Integration with Internal: Charging Device Reverse Blocking Diode Current Sensing Active Thermal Loop Charge Reduction Automatic Recharge Sequencing Battery Temperature Monitoring Full Battery Charge Auto Turn-Off / Sleep Mode Over-Voltage, Over-Current, and Over-Temperature Protection Power On Reset and Soft Start Serial Interface Status Report 12-Pin 3x3mm TDFN Package -40C to +85C Temperature Range
* * * * * * * * *
Applications
* * * * * * Cellular Telephones Digital Still Cameras Hand Held PCs MP3 Players Personal Data Assistants (PDAs) Other Lithium-Ion/Polymer Battery-Powered Devices
Typical Application
Adapter Present Enable Serial Interface
BATT+
ADPP# EN DATA TS BAT COUT 10F
+
BATT-
AAT3687
CT
Adapter
CIN 10F RSET
ADP ADPSET STAT1 GND STAT2
CT 0.1F
TEMP
RB1 LED1
RB2
Battery Pack
LED2
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PRODUCT DATASHEET
AAT3687
BatteryManagerTM
Pin Descriptions
Pin #
1 2 3 4 5 6 7 8 9 10 11 12 EP
Lithium-Ion/Polymer Battery Charger
Name
BAT ADP GND EN ADPP# TS DATA STAT2 STAT1 CT N/C ADPSET
Type
Out In Ground In Out In/Out Out Out Out In/Out
Function
Battery charging and sensing. Adapter input. Ground connection. AAT3687: Enable pin. Logic high enables the IC. AAT3687-1, AAT3687-2: Enable pin. Logic high enables the IC. EN tied to internal 4M pull-up resistor to ADP. Adapter present indicator. This pin is open drain until ADP pin reaches threshold. Connect to 10k NTC thermistor. Status report to microcontroller via serial interface: open drain. Battery charge status indicator pin to drive an LED: active low, open drain. Battery charge status indicator pin to drive an LED: active low, open drain. Timing capacitor to adjust internal watchdog timer. Set maximum charge time for adapter powered trickle, CC, and CV charge modes. If timing function is not needed, terminate this pin to ground. No connection. Use resistor at this pin to set adapter charging current. Exposed paddle (bottom); connect to GND directly beneath package.
In/Out
Pin Configuration
TDFN33-12 (Top View)
BAT ADP GND EN ADPP# TS
1 2 3 4 5 6
12 11 10 9 8 7
ADPSET N/C CT STAT1 STAT2 DATA
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3687.2008.04.1.12
PRODUCT DATASHEET
AAT3687
BatteryManagerTM
AAT3687 Feature Options
Product
AAT3687 AAT3687-1 AAT3687-2
Lithium-Ion/Polymer Battery Charger
Trickle Charge
Yes Yes No
Internal Pull-Up Resistor on EN Pin
No Yes Yes
Can Leave TS Pin Open
No Yes Yes
Absolute Maximum Ratings1
Symbol
VP VP VN TJ TLEAD
Description
ADP Input Voltage, <30ms, Duty Cycle <10% ADP Input Voltage, Continuous BAT, TS, ADPSET, ADPP#, DATA, CT, EN, STAT1, STAT2 Operating Junction Temperature Range Maximum Soldering Temperature (at leads)
Value
-0.3 to 7.0 -0.3 to 6.0 -0.3 to VP + 0.3 -40 to 150 300
Units
V V V C C
Thermal Information
Symbol
JA PD
Description
Maximum Thermal Resistance2 Maximum Power Dissipation
Value
50 2.0
Units
C/W W
1. Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at conditions other than the operating conditions specified is not implied. Only one Absolute Maximum Rating should be applied at any one time. 2. Mounted on an FR4 board.
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PRODUCT DATASHEET
AAT3687
BatteryManagerTM
Electrical Characteristics1
VADP = 5V, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = 25C. Symbol Description Conditions Min
4.0 Rising Edge Charge Current = 100mA AAT3687: VBAT = 4.25V AAT3687-1, AAT3687-2: VBAT = 4.25V VBAT = 4V, ADP Pin Open 4.158 AAT3687, AAT3687-1 Only 2.8 3.0 3.0 150 0.75 0.3 1 1.0 4.20 0.5 3.0 VBAT_EOC 0.1 100 CC Mode 10 2.0 4000 0.2 0.25 0.35 1500
Lithium-Ion/Polymer Battery Charger
Typ
Max
5.5
Units
V V V mV mA A A
Operation ADP Adapter Voltage Range VADPP Adapter Present Threshold Voltage Under-Voltage Lockout (UVLO) VUVLO UVLO Hysteresis Operating Current IOP ISLEEP Sleep Mode Current
1.5 1.0 3
ILeakage Reverse Leakage Current from BAT Pin Voltage Regulation End of Charge Voltage Accuracy VBAT_EOC1 VCH/VCH Output Charge Voltage Tolerance VMIN Preconditioning Voltage Threshold VRCH Battery Recharge Voltage Threshold
4.242 3.15
V % V V mA % V
Current Regulation ICH Charge Current ICH/ICH Charge Current Regulation Tolerance VADPSET ADPSET Pin Voltage KIA Current Set Factor: ICH/IADPSET Charging Devices Adapter Charging Transistor RDS(ON) On Resistance
VIN = 5.5V
1. The AAT3687 output charge voltage is specified over the 0 to 70C ambient temperature range; operation over the -40C to +85C temperature range is guaranteed by design.
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PRODUCT DATASHEET
AAT3687
BatteryManagerTM
Electrical Characteristics1
VADP = 5V, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = 25C. Symbol Description Conditions Min
1.6 0.4 AAT3687-1, AAT3687-2 Only; VEN = 5V ADPP# Pin Sinks 500A CT = 0.1F, VADP = 5.5V AAT3687, AAT3687-1 Only; CT = 0.1F, VADP = 5.5V CT = 0.1F, VADP = 5.5V STAT Pin Sinks 4mA 3.0 25 3.0 0.4 8.0 4.4 10 7.5 80 330 15 2.3 10 8 1.6 0.4 Status Request 200 50 20 90 110 85 145 10 0.4
Lithium-Ion/Polymer Battery Charger
Typ
Max
Units
V V A V Hours Minutes Hours V mA V % % A mV V mV mA mA V V ns s kHz C C C C
Logic Control / Protection Input High Threshold VEN(H) VEN(L) Input Low Threshold IEN(H) VADPP# TC TP TV VSTAT ISTAT VOVP ITK/ICHG ITERM/ICHG ITS TS1 TS2 IDATA IADPP# VDATA(H) VDATA(L) SQPULSE tPERIOD fDATA TREG TLOOP_IN TLOOP_OUT TOVSD EN Input Current Output Low Voltage Preconditioning Plus Constant Current Mode Time Out Preconditioning Time Out Constant Voltage Mode Time Out Output Low Voltage STAT Pin Current Sink Capability Over-Voltage Protection Threshold Pre-Charge Current Charge Termination Threshold Current Current Source from TS Pin TS Hot Temperature Fault TS Cold Temperature Fault DATA Pin Sink Current ADPP# Current Sink Input High Threshold Input Low Threshold Status Request Pulse Width System Clock Period Data Output Frequency Thermal Loop Regulation Thermal Loop Entering Threshold Thermal Loop Exiting Threshold Over-Temperature Shutdown Threshold
AAT3687, AAT3687-1 Only 70 310 2.2 3
Threshold Hysteresis Threshold Hysteresis DATA Pin is Active Low State ADPP# Pin is Active Low State
90 350 2.4
1. The AAT3687 output charge voltage is specified over the 0 to 70C ambient temperature range; operation over the -40C to +85C temperature range is guaranteed by design.
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PRODUCT DATASHEET
AAT3687
BatteryManagerTM
Typical Characteristics
Charge Current vs. RSET
10000 4.242
Lithium-Ion/Polymer Battery Charger
Battery Voltage vs. Supply Voltage
4.221
ICH (mA)
1000
VBAT (V)
100 10 1 10 100
4.200
4.179
4.158 4.5 4.75 5.0 5.25 5.5
RSET (k)
Supply Voltage (V)
End of Charge Voltage Regulation vs. Temperature
4.242
Preconditioning Threshold Voltage vs. Temperature
3.05 3.04
4.221
3.03 3.02
VBAT_EOC (V)
VMIN (V)
3.01 3.00 2.99 2.98 2.97 2.96
4.200
4.179
4.158 -50
2.95
-25 0 25 50 75 100
-50
-25
0
25
50
75
100
Temperature (C)
Temperature (C)
Pre-Charge Current vs. Temperature
(ADPSET = 8.06k)
120 1100 1080 110 1060 1040
Charge Current vs. Temperature
(ADPSET = 8.06k)
ICH (mA)
-25 0 25 50 75 100
ITK (mA)
1020 1000 980 960 940 920
100
90
80 -50
900 -50 -25 0 25 50 75 100
Temperature (C)
Temperature (C)
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PRODUCT DATASHEET
AAT3687
BatteryManagerTM
Typical Characteristics
Charge Current vs. Battery Voltage
(ADPSET = 8.06k; VIN = 5.0V)
1.2 1.0 0.8
Lithium-Ion/Polymer Battery Charger
Fast Charge Current vs. Supply Voltage
(ADPSET = 8.06k)
1200
VBAT = 3.3V
1000 800 600 400 200 0 2.5 2.9 3.3 3.7 4.1 4.5 4.0 4.5 5.0 5.5 6.0
0.6 0.4 0.2 0.0
ICH (mA)
VBAT = 3.9V VBAT = 3.5V
ICH (A)
Battery Voltage (V)
Supply Voltage (V)
VIH vs. Supply Voltage EN Pin (Rising)
1.4 1.3 1.2 1.1 1.4 1.3 1.2 1.1
VIL vs. Supply Voltage EN Pin (Falling)
VIH (V)
0.9 0.8 0.7 0.6 0.5 0.4 4.2 4.4 4.6 4.8 5.0 5.2 5.4 5.6 5.8 6.0
VIH (V)
1.0
-40C
+25C
1.0 0.9 0.8 0.7
-40C
+25C
+85C
0.6 0.5 0.4 4.2 4.4 4.6 4.8
+85C
5.0 5.2 5.4 5.6 5.8 6.0
Supply Voltage (V)
Supply Voltage (V)
Operating Current vs. ADPSET Resistor
0.80 10
Counter Timeout vs. Temperature
(CT = 0.1F)
Counter Timeout (%)
1000
0.70 0.60
8 6 4 2 0 -2 -4 -6 -8
IOP (mA)
0.50 0.40 0.30 0.20 0.10 0.00 1 10
Constant Current
Pre-Conditioning
100
-10 -50
-25
0
25
50
75
100
ADPSET Resistor (k)
Temperature (C)
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PRODUCT DATASHEET
AAT3687
BatteryManagerTM
Typical Characteristics
CT Pin Capacitance vs. Counter Timeout
2.0 1.8
Lithium-Ion/Polymer Battery Charger
Temperature Sense Output Current vs. Temperature
88
Capacitance (F)
1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 0 2 4 6 8 10
TS Pin Current (A)
86 84 82 80 78 76 74 72 -50 -25 0 25 50 75 100
Precondition Timeout
Precondition + Constant Current Timeout or Constant Voltage Timeout
Time (hours)
Temperature (C)
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PRODUCT DATASHEET
AAT3687
BatteryManagerTM
Functional Block Diagram
Constant Current Charge Control CV/ Precharge1
Lithium-Ion/Polymer Battery Charger
UVLO
4.2V
BAT
ADPSET ADP ADPP#
Voltage Sense
Current Compare
OverTemperature Protection
Reverse Blocking
80A
STAT1 STAT2 DATA EN
Charge Status
TS
Window Comparator
Serial Data
IC enable
Watchdog Timer
CT
GND
Functional Description
The AAT3687 is a highly integrated single-cell lithiumion/polymer battery charger IC designed to operate with standard AC adapter input sources, while requiring a minimum number of external components. The AAT3687 precisely regulates battery charge voltage and current for 4.2V lithium-ion/polymer battery cells. The adapter charge input constant current level can be programmed up to 1.5A for rapid charging applications. The AAT3687 is rated for operation from -40C to +85C. In the event of operating ambient temperatures exceeding the power dissipation abilities of the device package for a given constant current charge level, the charge control will enter into thermal regulation. When the system thermal regulation becomes active, the programmed constant current charge amplitude will be automatically reduced to a safe level for the current operating condition. Should the ambient operating temperature drop below the thermal loop threshold, the system will automatically resume charging at the full programmed con-
stant current level. This intelligent thermal management system permits the AAT3687 to operate and safely charge a battery cell over a wide range of ambient conditions while maximizing the greatest possible charge current for the given set of conditions. Status monitor output pins are provided to indicate the battery charge state by directly driving two external LEDs. A serial interface output is also available to report any one of 12 distinct charge states to the system microcontroller. Battery temperature and charge state are fully monitored for fault conditions. In the event of an over-voltage or over-temperature failure, the device will automatically shut down, thus protecting the charging device, control system, and the battery under charge. In addition to internal charge controller thermal protection, the AAT3687 also provides a temperature sense feedback function (TS pin) from the battery to shut down the device in the event the battery exceeds its own thermal limit during charging. All fault events are reported to the user either by the simple status LEDs or via the DATA pin function.
1. Precharge applies to AAT3687 and AAT3687-1 only.
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PRODUCT DATASHEET
AAT3687
BatteryManagerTM
Preconditioning Trickle Charge Phase Charge Complete Voltage Regulated Current I = Max CC Constant Current Charge Phase
Lithium-Ion/Polymer Battery Charger
Constant Voltage Charge Phase
Constant Current Mode Voltage Threshold
Trickle Charge and Termination Threshold
I = CC / 10
Figure 1: Current vs. Voltage Profile During Charging Phases.
Charging Operation
The AAT3687 has four basic modes for the battery charge cycle: pre-conditioning / trickle charge; constant current / fast charge; constant voltage; and end of charge (see Figure 1.) (AAT3687-2 does not have trickle charge.)
constant current fast charging phase. The fast charge constant current (ICC) amplitude is programmed by the user via the RSET resistor. The AAT3687 remains in the constant current charge mode until the battery reaches the voltage regulation point, VBAT.
Battery Preconditioning
Before the start of charging, the AAT3687 checks several conditions in order to assure a safe charging environment. The input supply must be above the minimum operating voltage, or under-voltage lockout threshold (VUVLO), for the charging sequence to begin. Also, the cell temperature, as reported by a thermistor connected to the TS pin from the battery, must be within the proper window for safe charging. When these conditions have been met and a battery is connected to the BAT pin, the AAT3687 checks the state of the battery. If the cell voltage is below the preconditioning voltage threshold (VMIN), the charge control begins preconditioning the cell. The battery preconditioning trickle charge current is equal to the fast charge constant current divided by 10. For example, if the programmed fast charge current is 1.5A, then the preconditioning mode (trickle charge) current will be 150mA. Cell preconditioning is a safety precaution for deeply discharged battery cells and also aids in limiting power dissipation in the pass transistor when the voltage across the device is at the greatest potential.
Constant Voltage Charging
The system transitions to a constant voltage charging mode when the battery voltage reaches the output charge regulation threshold (VBAT) during the constant current fast charge phase. The regulation voltage level is factory programmed to 4.2V (1%). Charge current in the constant voltage mode drops as the battery cell under charge reaches its maximum capacity.
End of Charge Cycle Termination and Recharge Sequence
When the charge current drops to 7.5% of the programmed fast charge current level in the constant voltage mode, the device terminates charging and goes into a sleep state. The charger will remain in a sleep state until the battery voltage decreases to a level below the battery recharge voltage threshold (VRCH). When the input supply is disconnected, the charger will automatically transition into a power-saving sleep mode. Only consuming an ultra-low 0.3A in sleep mode (1A for AAT3687-1 and AAT3687-2), the AAT3687 minimizes battery drain when it is not charging. This feature is particularly useful in applications where the input supply level may fall below the battery charge or under-voltage lockout level. In such cases where the AAT3687 input voltage drops, the device will enter sleep mode and automatically resume charging once the input supply has recovered from the fault condition.
Fast Charge / Constant Current Charging
Battery cell preconditioning continues until the voltage on the BAT pin exceeds the preconditioning voltage threshold (VMIN). At this point, the AAT3687 begins the
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PRODUCT DATASHEET
AAT3687
BatteryManagerTM
System Operation Flow Chart
Yes
Lithium-Ion/Polymer Battery Charger
Yes No No
Enable
No Timing Yes Yes Expire Yes No No
Yes (AAT3687) No
Yes
Set
No Yes
BAT_EOC
No Yes
TERM
No
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PRODUCT DATASHEET
AAT3687
BatteryManagerTM
Application Information
Adapter Power Input
Constant current charge levels up to 1.5A may be programmed by the user when powered from a sufficient input power source. The AAT3687 will operate from the adapter input over a 4.0V to 5.5V range. The constant current fast charge current for the adapter input is set by the RSET resistor connected between the ADPSET and ground. Refer to Table 1 for recommended RSET values for a desired constant current charge level. The presence of voltage on the adapter input is indicated by the ADPP# pin function. This indicator pin uses an internal open drain device that will pull the ADPP# pin low when voltage is detected on the ADP pin. The precise charging function of the AAT3687 may be read from the DATA pin and/or status LEDs. Please refer to the Battery Charge Status Indication discussion for further details on data reporting.
Lithium-Ion/Polymer Battery Charger
Adapter Input Charge Inhibit and Resume
The AAT3687 has a UVLO and power on reset feature so that the charger will suspend charging and shut down if the input supply to the adapter pin drops below the UVLO threshold. When power is re-applied to the adapter pin or the UVLO conditions recovers, the system charge control will assess the state of charge on the battery cell and will automatically resume charging in the appropriate mode for the condition of the battery.
Enable / Disable
The AAT3687 provides an enable function to control the charger IC on and off. The enable (EN) pin is active high. When pulled to a logic low level, the AAT3687 will be shut down and forced into the sleep state. Charging will be halted regardless of the battery voltage or charging state. When the device is re-enabled, the charge control circuit will automatically reset and resume charging functions with the appropriate charging mode based on the battery charge state and measured cell voltage on the BAT pin.
Thermal Loop Control
Due to the integrated nature of the linear charging control pass device for the adapter input, a special thermal loop control system has been employed to maximize charging current under all operating conditions. The thermal management system measures the internal circuit die temperature and reduces the fast charge current when the device exceeds a preset internal temperature control threshold. Once the thermal loop control becomes active, the fast charge current is initially reduced by a factor of 0.44. The initial thermal loop current can be estimated by the following equation: Eq. 1: ITLOOP = ICC * 0.44 The thermal loop control re-evaluates the circuit die temperature in 330ms intervals and adjusts the fast charge current back up in small steps to the full fast charge current level or until an equilibrium current is discovered and maximized for the given ambient temperature condition. The thermal loop controls the system charge level; therefore, the AAT3687 will always provide the highest level of constant current in the fast charge mode possible for any given ambient temperature condition.
Programming Charge Current
The fast charge constant current charge level is user programmed with a set resistor placed between the ADPSET pin and ground. The accuracy of the fast charge, as well as the preconditioning trickle charge current, is dominated by the tolerance of the set resistor used. For this reason, a 1% tolerance metal film resistor is recommended for the set resistor function. Fast charge constant current levels from 50mA to 1.5A can be set by selecting the appropriate resistor value from Table 1. ADP RSET (k)
N/A N/A 84.5 43.2 28.0 21.0 16.9 13.3 11.5
ICC
50 75 100 200 300 400 500 600 700
ICC
800 900 1000 1100 1200 1300 1400 1500
ADP RSET (k)
10.2 9.09 8.06 7.32 6.65 6.04 5.62 5.36
Table 1: Recommended RSET Values.
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PRODUCT DATASHEET
AAT3687
BatteryManagerTM
10000
Lithium-Ion/Polymer Battery Charger
The constant current provided to charge the timing capacitor is very small, and this pin is susceptible to noise and changes in capacitance value. Therefore, the timing capacitor should be physically located on the printed circuit board layout as close as possible to the CT pin. Since the accuracy of the internal timer is dominated by the capacitance value, a 10% tolerance or better ceramic capacitor is recommended. Ceramic capacitor materials, such as X7R and X5R types, are a good choice for this application.
ICH (mA)
1000
100
10 1 10 100
RSET (k)
Over-Voltage Protection
An over-voltage event is defined as a condition where the voltage on the BAT pin exceeds the maximum battery charge voltage and is set by the over-voltage protection threshold (VOVP). If an over-voltage condition occurs, the AAT3687 charge control will shut down the device until the voltage on the BAT pin drops below VOVP. The AAT3687 will resume normal charging operation after the over-voltage condition is removed. During an over-voltage event, the STAT LEDs will report a system fault, and the actual fault condition can be read via the DATA pin signal.
Figure 2: IFASTCHARGE vs. RSET.
Protection Circuitry
Programmable Watchdog Timer
The AAT3687 contains a watchdog timing circuit to shut down charging functions in the event of a defective battery cell not accepting a charge over a preset period of time. Typically, a 0.1F ceramic capacitor is connected between the CT pin and ground. When a 0.1F ceramic capacitor is used, the device will time out a shutdown condition if the trickle charge mode exceeds 25 minutes (AAT3687 and AAT3687-1 only) and a combined trickle charge plus fast charge mode of 3 hours. When the device transitions to the constant voltage mode, the timing counter is reset and will time out after an additional 3 hours if the charge current does not drop to the charge termination level. Mode
Trickle Charge (TC) Time Out Trickle Charge (TC) + Fast Charge (CC) Time Out Constant Voltage (VC) Mode Time Out
Over-Temperature Shutdown
The AAT3687 has a thermal protection control circuit which will shut down charging functions should the internal die temperature exceed the preset thermal limit threshold.
Time
25 minutes (AAT3687 and AAT3687-1 only) 3 hours 3 hours
Battery Temperature Fault Monitoring
In the event of a battery over-temperature condition, the charge control will turn off the internal pass device and report a battery temperature fault on the DATA pin function. The STAT LEDs will also display a system fault. After the system recovers from a temperature fault, the device will resume charging operation. The AAT3687 checks battery temperature before starting the charge cycle, as well as during all stages of charging. This is accomplished by monitoring the voltage at the TS pin. This system is intended for use with negative temperature coefficient thermistors (NTC) which are typically integrated into the battery package. Most of the commonly used NTC thermistors in battery packs are approximately 10k at room temperature (25C). The TS pin has been specifically designed to source 80A of current to the thermistor. The voltage on the TS pin resulting from the resistive load should stay within a window of 335mV to 2.32V. If the battery becomes too hot during charging due to an internal fault or excessive fast charge
Table 2: Summary for a 0.1F Ceramic Capacitor Used for the Timing Capacitor. The CT pin is driven by a constant current source and will provide a linear response to increases in the timing capacitor value. Thus, if the timing capacitor were to be doubled from the nominal 0.1F value, the time-out periods would be doubled. If the programmable watchdog timer function is not needed, it can be disabled by terminating the CT pin to ground. The CT pin should not be left floating or unterminated, as this will cause errors in the internal timing control circuit.
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PRODUCT DATASHEET
AAT3687
BatteryManagerTM
current, the thermistor will heat up and reduce in value, pulling the TS pin voltage lower than the TS1 threshold, and the AAT3687 will signal the fault condition. If the use of the TS pin function is not required by the system, it should be terminated to ground using a 10k resistor. Alternatively, on the AAT3687-1 and AAT3687-2, the TS pin may be left open.
Lithium-Ion/Polymer Battery Charger
Example: Eq. 3: RB(STAT1) =
(5.5V - 2.0V) = 1.75k 2mA
Note: Red LED forward voltage (VF) is typically 2.0V @ 2mA Event Description
Charge Disabled or Low Supply Charge Enabled Without Battery Battery Charging Charge Completed Fault
Battery Charge Status Indication
The AAT3687 indicates the status of the battery under charge with two different systems. First, the device has two status LED driver outputs. These two LEDs can indicate simple functions such as no battery charge activity, battery charging, charge complete, and charge fault. The AAT3687 also provides a bi-directional data reporting function so that a system microcontroller can interrogate the DATA pin and read any one of 12 system states.
STAT1
Off Flash1 On Off On
STAT2
Off Flash1 Off On On
Table 3: LED Status Indicator.
Digital Charge Status Reporting
The AAT3687 has a comprehensive digital data reporting system by use of the DATA pin feature. This function can provide detailed information regarding the status of the charging system. The DATA pin is a bi-directional port which will read back a series of data pulses when the system microcontroller asserts a request pulse. This single strobe request protocol will invoke one of 12 possible return pulse counts that the system microcontroller can look up based on the serial report data listed in Table 4. N
1 2 3 4 5 6 7 8 9 10 11 12 23
Status Indicator Display
Simple system charging status states can be displayed using one or two LEDs in conjunction with the STAT1 and STAT2 pins on the AAT3687. These two pins are simple open drain switches used to connect the LED cathodes to ground. It is not necessary to use both display LEDs if a user simply wants to have a single lamp to show "charging" or "not charging." This can be accomplished by using the STAT1 pin and a single LED. Using two LEDs and both STAT pins simply gives the user more information to the charging states. Refer to Table 3 for LED display definitions. The LED anodes should be connected to VADP. The LEDs should be biased with as little current as necessary to create reasonable illumination; therefore, a ballast resistor should be placed between the LED cathodes and the STAT1/2 pins. LED current consumption will add to the overall thermal power budget for the device package, hence it is good to keep the LED drive current to a minimum. 2mA should be sufficient to drive most low-cost green or red LEDs. It is not recommended to exceed 8mA for driving an individual status LED. The required ballast resistor values can be estimated using the following formulas: Eq. 2: RB(STAT1/2) =
DATA Report Status
Chip Over-Temperature Shutdown. Battery Temperature Fault. Over-Voltage Turn Off. Not Used. ADP Watchdog Time-Out in Battery Condition Mode. ADP Battery Condition Mode. ADP Watchdog Time-Out in Constant Current Mode. ADP Thermal Loop Regulation in Constant Current Mode. ADP Constant Current Mode. ADP Watchdog Time-Out in Constant Voltage Mode. ADP Constant Voltage Mode. ADP End of Charging. Data Report Error.
Table 4: Serial Data Report Table.
(VADP - VF(LED)) ILED(STAT1/2)
1. Flashing rate depends on output capacitance.
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3687.2008.04.1.12
PRODUCT DATASHEET
AAT3687
BatteryManagerTM
1.8V to 5.0V
Lithium-Ion/Polymer Battery Charger
IN
AAT3687 Status Control
OUT
RPULL_UP DATA Pin
GPIO
IN
OUT
P GPIO Port
Figure 3: Data Pin Application Circuit.
The DATA pin function logic is active low and should normally be pulled high to VADP. This data line can also be pulled high to the same level as the high state for the logic I/O port on the system microcontroller. In order for the DATA pin control circuit to generate clean, sharp edges for the data output, and to maintain the integrity of the data timing for the system, the pull-up resistor on the data line should be low enough in value so that the DATA signal returns to the high state without delay. If the pull-up resistor is too high, the strobe pulse from the system microcontroller could exceed the maximum pulse time and the DATA output control could issue false status reports. A 1.5k resistor is recommended when pulling the DATA pin high to 5.0V on the VADP input. If the data line is pulled high to a voltage level less than 5.0V, the pull-up resistor can be calculated based on a recom-
mended minimum pull-up current of 3mA. Use the following formula: Eq. 4: RPULL-UP
VPULL-UP 3mA
Data Timing
The system microcontroller should assert an active low data request pulse for minimum duration of 200ns; this is specified by TLO(DATA). Upon sensing the rising edge of the end of the data request pulse, the AAT3687 status data control will reply the data word back to the system microcontroller after a delay specified by the data report time specification TDATA(RPT). The period of the following group of data pulses will be specified by TDATA.
Timing Diagram
SQ
SQPULSE System Reset System Start PDATA
CK
TSYNC TLAT TOFF
Data
TDATA(RPT) = TSYNC + TLAT < 2.5 PDATA TOFF > 2 PDATA
N=1
N=2
N=3
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PRODUCT DATASHEET
AAT3687
BatteryManagerTM
Thermal Considerations
The AAT3687 is offered in a 3x3mm TDFN package which can provide up to 2.0W of power dissipation when it is properly bonded to a printed circuit board and has a maximum thermal resistance of 50C/W. Many considerations should be taken into account when designing the printed circuit board layout, as well as the placement of the charger IC package in proximity to other heat generating devices in a given application design. The ambient temperature around the charger IC will also have an effect on the thermal limits of a battery charging application. The maximum limits that can be expected for a given ambient condition can be estimated by the following discussion. First, the maximum power dissipation for a given situation should be calculated: Eq. 5: PD = [(VIN - VBAT) * ICC + (VIN * IOP)] Where: PD VIN VBAT ICC IOP = = = = Total Power Dissipation by the Device Input Voltage Amplitude, VADP Battery Voltage as Seen at the BAT Pin Maximum Constant Fast Charge Current Programmed for the Application = Quiescent Current Consumed by the Charger IC for Normal Operation Eq. 8: TA = 110C - (50C/W * 1.40375W)
Lithium-Ion/Polymer Battery Charger
Given: VADP VBAT ICC IOP TJ JA = = = = = = 5.0V 3.6V 1A 0.75mA 110C 50C/W
Using Equation 5, calculate the device power dissipation for the stated condition: Eq. 7: PD = (5.0V - 3.6V)(1A) + (5.0V * 0.75mA)
= 1.40375W
The maximum ambient temperature before the AAT3687 thermal loop becomes active can now be calculated using Equation 6:
= 39.8125C
Therefore, under the stated conditions for this worst case power dissipation example, the AAT3687 will enter the thermal loop and lower the fast charge constant current when the ambient operating temperature rises above 39.8C.
Next, the maximum operating ambient temperature for a given application can be estimated based on the thermal resistance of the 3x3mm TDFN package when sufficiently mounted to a PCB layout and the internal thermal loop temperature threshold. Eq. 6: TA = TJ - (JA * PD) Where: TA = Ambient Temperature in C TJ = Maximum Device Junction Temperature Below the Thermal Loop Threshold PD = Total Power Dissipation by the Device JA = Package Thermal Resistance in C/W Example: For an application where the fast charge current for the adapter mode is set to 1A, VADP = 5.0V and the battery voltage at 3.6V, what is the maximum ambient temperature at which the thermal loop will become active?
Capacitor Selection
Input Capacitor
In general, it is good design practice to place a decoupling capacitor between the ADP pin and ground. An input capacitor in the range of 1F to 22F is recommended. If the source supply is unregulated, it may be necessary to increase the capacitance to keep the input voltage above the under-voltage lockout threshold during device enable and when battery charging is initiated. If the AAT3687 adapter input is to be used in a system with an external power supply source, such as a typical AC-to-DC wall adapter, then a CIN capacitor in the range of 10F should be used. A larger input capacitor in this application will minimize switching or power transient effects when the power supply is "hot plugged" in.
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PRODUCT DATASHEET
AAT3687
BatteryManagerTM
Output Capacitor
The AAT3687 only requires a 1F ceramic capacitor on the BAT pin to maintain circuit stability. This value should be increased to 10F or more if the battery connection is made any distance from the charger output. If the AAT3687 is to be used in applications where the battery can be removed from the charger, such as with desktop charging cradles, an output capacitor greater than 10F may be required to prevent the device from cycling on and off when no battery is present.
Lithium-Ion/Polymer Battery Charger
Printed Circuit Board Layout Considerations
For the best results, it is recommended to physically place the battery pack as close as possible to the AAT3687 BAT pin. To minimize voltage drops on the PCB, keep the high current carrying traces adequately wide. For maximum power dissipation of the AAT3687 3x3mm TDFN package, the metal substrate should be solder bonded to the board. It is also recommended to maximize the substrate contact to the PCB ground plane layer to further increase local heat dissipation. Refer to the AAT3687 evaluation board for a good layout example (see Figures 4 and 5).
AAT3687 Evaluation Board Layout
Figure 4: AAT3687 Evaluation Board Component Side Layout.
Figure 5: AAT3687 Evaluation Board Solder Side Layout.
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PRODUCT DATASHEET
AAT3687
BatteryManagerTM
AAT3687 Evaluation Board Schematic Diagram
TermB2
1 ADP 2 GNDTermB2
Lithium-Ion/Polymer Battery Charger
C1 10F
J1 ON/OFF
123
RED GRN RED LED D3 LED D2 LED D1
R3 1.5k
R4 1.5k
R5 1.5k
R7 1.5k
R1 Open
4 2
U1
(TDFN33-12)
EN ADP BAT
ADPP# STAT2 STAT1 DATA
5 8 9 7
TermB3 BAT TS GND
1 3 2 1
DATA
AAT3687
6
TS
GND
3
ADPSET
CT
10
12
C2 10F R2 10k R6 8.06k C3 0.1F
SW1
CT
AAT3687 Evaluation Board Bill of Materials (BOM)
Quantity
1 1 1 2 1 2 1 1 1 1 4 1 1
Description
Test Pin Connecting Terminal Block, 2.54mm, 2 Position Connecting Terminal Block, 2.54mm, 3 Position Capacitor, Ceramic, 10F 6.3V 10% X5R 0805 Capacitor, Ceramic, 0.1F 10% 16V X7R 0603 Typical Red LED, Ultra-Bright Typical Green LED Header, 3-Pin Resistor, 10k, 1/16W 5% 0603 SMD Resistor, 8.06k, 1/16W 1% 0603 SMD Resistor, 1.5k, 1/16W 5% 0603 SMD Switch Tact 6mm SPST H = 5.0mm AAT3687 Lithium-Ion/Polymer Battery Charger
Desig.
DATA ADP, GND BAT, GND, TS C1, C2 C3 D1, D3 D2 J1 R2 R6 R3, R4, R5, R7 SW1 U1
Footprint
PAD TBLOK2 TBLOK3 0805 0603 1206LED 1206LED HEADER2MM-3 0603 0603 0603 Switch TDFN33-12
Manufacturer
Mill-Max Phoenix Contact Phoenix Contact Murata Murata Chicago Miniature Lamp Chicago Miniature Lamp Sullins Panasonic/ECG Panasonic/ECG Panasonic/ECG ITT Industries/ C&K Div AnalogicTech
Part Number
6821-0-0001-00-00-08-0 277-1274-ND 277-1273-ND GRM219R60J106KE19 GRM188R71C104KA01D CMD15-21SRC/TR8 CMD15-21VGC/TR8 6821-0-0001-00-00-08-0 P10KCFCT-ND P8.06KHCT-ND P1.5KCGCT-ND CKN9012-ND AAT3687IWP-4.2
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3687.2008.04.1.12
PRODUCT DATASHEET
AAT3687
BatteryManagerTM
Ordering Information
Trickle Charge
Yes Yes No
Lithium-Ion/Polymer Battery Charger
Package
TDFN33-12 TDFN33-12 TDFN33-12
Marking1
PIXYY TQXYY RTXYY
Part Number (Tape and Reel)2
AAT3687IWP-4.2-T1 AAT3687IWP-4.2-1-T1 AAT3687IWP-4.2-2-T1
All AnalogicTech products are offered in Pb-free packaging. The term "Pb-free" means semiconductor products that are in compliance with current RoHS standards, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. For more information, please visit our website at http://www.analogictech.com/about/quality.aspx.
Package Information3
TDFN33-12
Index Area Detail "A" 0.43 0.05
0.1 REF 3.00 0.05 2.40 0.05 C0.3 0.45 0.05
Pin 1 Indicator (optional)
3.00 0.05
1.70 0.05
Top View
Bottom View Detail "A"
0.75 0.05
0.05 0.05
Side View
All dimensions in millimeters.
1. XYY = assembly and date code. 2. Sample stock is generally held on part numbers listed in BOLD. 3. The leadless package family, which includes QFN, TQFN, DFN, TDFN and STDFN, has exposed copper (unplated) at the end of the lead terminals due to the manufacturing process. A solder fillet at the exposed copper edge cannot be guaranteed and is not required to ensure a proper bottom solder connection.
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0.23 0.05
0.23 0.05
19
PRODUCT DATASHEET
AAT3687
BatteryManagerTM Lithium-Ion/Polymer Battery Charger
Advanced Analogic Technologies, Inc. 3230 Scott Boulevard, Santa Clara, CA 95054 Phone (408) 737-4600 Fax (408) 737-4611
(c) Advanced Analogic Technologies, Inc. AnalogicTech cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an AnalogicTech product. No circuit patent licenses, copyrights, mask work rights, or other intellectual property rights are implied. AnalogicTech reserves the right to make changes to their products or specifications or to discontinue any product or service without notice. Except as provided in AnalogicTech's terms and conditions of sale, AnalogicTech assumes no liability whatsoever, and AnalogicTech disclaims any express or implied warranty relating to the sale and/or use of AnalogicTech products including liability or warranties relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right. In order to minimize risks associated with the customer's applications, adequate design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards. Testing and other quality control techniques are utilized to the extent AnalogicTech deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily performed. AnalogicTech and the AnalogicTech logo are trademarks of Advanced Analogic Technologies Incorporated. All other brand and product names appearing in this document are registered trademarks or trademarks of their respective holders.
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